Assembly and method for stiffening a flexible pipe

ABSTRACT

An assembly and method for stiffening a flexible member according to which a stiffening member and an adapter surround the flexible member and an insert extends in an annulus between the adapter and the flexible member.

BACKGROUND

This invention relates to an assembly and method for stiffening a flexible pipe.

Flexible pipes, or other flexible components such as tubes, risers, umbilicals, cables, and the like (hereinafter collectively referred to as “flexible members”) are often subjected to substantial bending moments. For example, when flexible members are used in subsea operations to transfer fluids, the hydrodynamic effects of water current can cause substantial bending moments on the flexible members, especially at their termination points. This can lead to fatigue failure in the flexible member.

To guard against any damage that would be caused by these bending moments, bend stiffeners are often placed around the flexible members to increase their stiffness and thus decrease the bending moments. A typical bend stiffener is formed by an elastomer tapered sleeve that extends around the flexible pipe and is secured to the pipe by an adapter. However, the internal diameter of the adapter usually engages the outer surface of the flexible member, which can cause excessive wear on the flexible member that could compromise its integrity.

Therefore, what is needed is an adapter for a flexible member that eliminates this problem.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial elevational/partial cross-sectional view of an assembly according to an embodiment of the invention.

FIG. 2 is a top plan view of the assembly of FIG. 1.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a flexible member, in the form of a pipe 10, is shown, and it is understood that it is disposed in an environment in which it is subjected to the bending moments discussed above. A cylindrical bend stiffener 12 surrounds a portion of the pipe 10 that needs to be stiffened, such as a joint between two adjacent sections of the pipe, an area near a termination point of the pipe, or the like. The inner surface of the bend stiffener 12 is in contact with the corresponding outer surface of the pipe 10, and it is understood that the outer surface of the remaining portion (not shown) of the bend stiffener 12 can be tapered slightly in a direction towards the pipe. Preferably, the bend stiffener 12 is fabricated from an elastomer material, such as polyurethane or polychloroprene.

A mounting ring 16 extends around the pipe 10 and is bolted to the upper end of the bend stiffener, as viewed in FIG. 1.

The lower end of a cylindrical adapter 20 is welded to the upper surface of the ring 16 by an annular weldment 22. The inner diameter of the adapter 20 extends in a spaced relation to the corresponding outer surface of the pipe 10 to form an annulus which receives a cylindrical insert 24. The inner surface of the insert 24 is in contact with the corresponding outer surface of the pipe 10, and the outer surface of the insert is in contact with the corresponding inner surface of the adapter 20. The inner surface of the lower end portion of the insert 24 is welded to the lower end of the adapter 20 and to the upper surface of the ring 16 by an annular weldment 26.

The insert 24 is split, e.g., it is formed by two sections 24 a and 24 b (FIG. 2), each having a semi-circular cross section, to facilitate the assembly of the insert in the above annulus between the pipe 10 and the adapter 20. Preferably the insert 24 is fabricated from polyurethane.

The outer surface of the insert 24 is stepped (FIG. 1), and an annular tapered flange 30 is welded to the shoulder formed at the step. In the event an outer tube structure (not shown) is placed around the pipe 10, or a portion of the pipe, above the bend stiffener 12, the flange 30 permits an enlarged mouth of the tube structure to be secured to the adapter 20 and the bend stiffener 12 by a tube bellmouth system (not shown).

An annular flange 24 a extends radially outwardly from the upper end of the insert 24, and four padkeys 32 a-32 d (FIG. 2), spaced at ninety degree intervals, are bolted to the flange to receive a tow line, or the like (not shown).

The assembly formed by the bend stiffener 12, the adapter 20, and the insert 24 stiffens the portion of the pipe 10 extending within the assembly while the insert eliminates any engagement, and resultant wear, between the adapter and the pipe.

It is understood that variations may be made in the above, without departing from the scope of the invention. For example, spatial references, such as “upper”, “lower”, “vertical”, “angular”, “radial” etc. are for the purpose of illustration only and do not limit the specific orientation or location of the structure described above. Also, the weldments 22 and 26 can be replaced by any other type of connectors such as bolts, etc.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents. 

1. An assembly for stiffening a flexible member, the assembly comprising a stiffening member surrounding a portion of the flexible member, an adapter secured to the stiffening member and surrounding a further portion of the flexible member in a spaced relation thereto to form an annulus, and an insert disposed in the annulus, wherein the insert extends along the annulus over said portion of the flexible member surrounded by the adapter.
 2. The assembly of claim 1 wherein an inner surface of said stiffening member contacts an outer surface of the flexible member.
 3. The assembly of claim 1 wherein said a portion comprises the portion of the flexible member surrounded by the stiffening member between first and second ends thereof.
 4. The assembly of claim 1 wherein the insert is fabricated from a material to eliminate wear of said another portion of the flexible pipe.
 5. The assembly of claim 4 wherein the insert is fabricated from polyurethane.
 6. The assembly of claim 1 wherein the insert comprises an annular flange extending radially outwardly from an upper end of the insert.
 7. The assembly of claim 1 further comprising a plurality of pad keys to receive a tow line.
 8. The assembly of claim 1 wherein the flexible member is a pipe and wherein the stiffening member, the adapter, and the insert are cylindrical.
 9. The assembly of claim 8 wherein the insert is formed by two semi-circular insert portions.
 10. A method for stiffening a flexible member, the method comprising surrounding a portion of the flexible member with a stiffening member, surrounding a further portion of the flexible member with an adapter secured to the stiffening member that extends in a spaced relation to the flexible member to form an annulus, securing the adapter to the stiffening member, and inserting an insert into the annulus, whereby the insert extends along the annulus over the portion of flexible member surrounded by the adapter.
 11. The method of claim 10 further comprising supporting an outer surface of the flexible member with an inner surface of the stiffening member.
 12. The method of claim 10 further comprising, via said insert, preventing the adapter from contacting said further portion of the flexible member. 